Mobile phones are arguably the devices on which we depend the most nowadays, however one of the biggest problems of these devices is the duration of the batteries. For most of us, it is nothing more than a dream to have your phone work without a battery. Nowadays, the wireless charge or the fast charge help to minimize this problem, but it does not solve it fully.
Nevertheless, a group of researchers at the University of Washington have recently developed a mobile phone that can work without a battery, and is able to collect a few microwatts of power from radio signals or ambient light. This has been developed with the objective of finishing with the problem of the limited duration of a battery of a mobile phone.
This new design can sense speech, trigger the earphones and switch between uplink and downlink communications, all in real time. This system optimizes the transmission and reception of voice at the same time that it collects power, which enables it to operate continuously.
This first prototype is built without an external cover, so it consists on a printed circuit board.
One of the tests that was done, was a Skype call, proving that this device can receive and transmit voice, and communicate with a base station at a distance of 15 meters.
In order to achieve such a low consumption of energy that is required for the device to work, it was necessary to rethink the way mobile phones work. The group of researchers decided to eliminate the process that most energy consumes: the process that converts sound analog signals into digital data.
This mobile phone takes advantage of the small vibrations that are produced in the microphone or speaker when a person speaks or listens to a conversation.
In order to transmit voice, the mobile phone uses the vibrations of the microphone to code voice patterns in the reflected signals. To receive voice, it converts coded radio signals into sound vibrations that are captured by the speaker of the phone. In this prototype, the user has to press a button to change between these two modes of “transmission” and “reception”. This reminds us of the ‘walkie talkie’ method.
The creators of this new device have plans for the future too, for a further step, improving the signal of the device and to aggregate a method that allows to encrypt calls, as well as a screen of electronic ink, in order to transmit video and reproduce it on this screen.
Jimena, Consultant, Leyton Spain